Touch apparatus, capacitive touch sensing circuit thereof, and touch sensing method using the same

ABSTRACT

A touch apparatus, a capacitive touch sensing circuit of the touch apparatus, and a touch sensing method are provided. The capacitive touch sensing circuit includes a switching capacitor integrating circuit, an encoding circuit, a feedback circuit, and a decoding circuit. The switching capacitor integrating circuit receives an input signal and integrates the input signal to generate an output signal. The encoding circuit receives and encodes the output signal to generate an encoded result. The feedback circuit provides a charge dissipation path for discharging charges from the switching capacitor integrating circuit, and the feedback circuit receives the encoded result and adjusts a charge dissipation ability provided by the charge dissipation path according to the encoded result. The decoding circuit receives and decodes the output signal to generate a touch detecting result.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 104137107, filed on Nov. 11, 2015. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

Field of Invention

The invention relates to a capacitive touch sensing circuit, and moreparticularly, to a 1-bit sigma delta capacitive touch sensing circuit.

Description of Related Art

With the popularity of electronic products, a well-functionedhuman-machine interface has become indispensible in every electronicapparatus, and capacitive touch panels are commonly applied in theexisting electronic apparatuses.

According to the related art, equipping the capacitive touch panel witha 1-bit sigma delta capacitive touch sensing circuit has been proposed,so as to perform touch sensing actions. In terms of the dimension of thecircuit, the power consumption, or the immunity to noise interference,the 1-bit sigma delta capacitive touch sensing circuit is superior tothe conventional analog-to-digital touch sensing circuit. However, sincethe 1-bit sigma delta capacitive touch sensing circuit provides thefeedback circuit with constant charge dissipation according to therelated art, the 1-bit sigma delta capacitive touch sensing circuitcannot guarantee both of the high resolution and the large detectablerange while detecting variations of capacitance, thus lessening theefficiency.

SUMMARY

The present invention is directed to a capacitive touch sensing circuitand sensing method thereof, which are able to effectively increase thesensing resolution and the detectable range while variations ofcapacitance are being detected.

The present invention is further directed to a touch apparatus using thecapacitive sensing circuit and the touch sensing method of thecapacitive touch sensing circuit, so as to effectively increase thesensitivity and the detectable range while variations of capacitance arebeing detected.

In an embodiment of the present invention, a capacitive touch sensingcircuit that includes a switching capacitor integrating circuit, anencoding circuit, a feedback circuit, and a decoding circuit isprovided. The switching capacitor integrating circuit is coupled to ato-be-tested capacitive touch unit that receives an input signal, andthe switching capacitor integrating circuit integrates the input signalto generate an output signal. The encoding circuit is coupled to theswitching capacitor integrating circuit to receive the output signal andencode the output signal to generate an encoded result. The feedbackcircuit is coupled to the switching capacitor integrating circuit andthe encoding circuit and provides the switching capacitor integratingcircuit with a charge dissipation path for discharging charges from theswitching capacitor integrating circuit, and the feedback circuitreceives the encoded result and adjusts a charge dissipation abilityprovided by the charge dissipation path according to the encoded result.The encoding circuit is coupled to the switching capacitor integratingcircuit to receive the output signal and decode the output signal togenerate a touch detecting result.

In an embodiment of the present invention, a touch display apparatusincludes a display panel and at least one capacitive touch sensingcircuit described above. The touch panel includes a plurality ofcapacitive touch units. The at least one capacitive touch sensingcircuit is coupled to the to-be-tested capacitive touch unit of one ofthe capacitive touch units.

In an embodiment of the present invention, a capacitive touch sensingmethod includes: receiving an input signal by a to-be-tested capacitivetouch unit, providing a switching capacitor integrating circuit, andintegrating the input signal by the switching capacitor integratingcircuit, so as to generate an output signal; encoding the output signalto generate an encoded result; providing the switching capacitorintegrating circuit with a charge dissipation path for dischargingcharges from the switching capacitor integrating circuit and adjusting acharge dissipation ability provided by the charge dissipation pathaccording to the encoded result; decoding the output signal to generatea touch detecting result.

In view of the above, the encoding circuit provided herein encodes theoutput signal and thereby generates the encoded result. The chargedissipation ability of the charge dissipation path provided by thefeedback circuit can be dynamically adjusted according to the encodedresult. That is, the charge dissipation mechanism provided herein can bedynamically adjusted in response to the load current, and the capacitivetouch sensing circuit can detect minor variations in the capacitanceeven in case of significant transfer capacitance; as such, therequirements for highly sensing resolution and large detectable rangecan be satisfied.

Several exemplary embodiments accompanied with figures are described indetail below to further describe the disclosure in details.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understanding,and are incorporated in and constitute a part of this specification. Thedrawings illustrate exemplary embodiments and, together with thedescription, serve to explain the principles of the invention.

FIG. 1 is a schematic view illustrating a capacitive touch sensingcircuit according to an embodiment of the present invention.

FIG. 2 is a schematic view illustrating a capacitive touch sensingcircuit according to another embodiment of the present invention.

FIG. 3 is a schematic view illustrating a capacitive touch sensingcircuit according to still another embodiment of the present invention.

FIG. 4 is a schematic view illustrating a capacitive touch sensingcircuit according to still another embodiment of the present invention.

FIG. 5 illustrates waveforms of encoding actions of an encoding circuitaccording to an embodiment of the present invention.

FIG. 6 is a schematic view illustrating a touch apparatus according toan embodiment of the present invention.

FIG. 7 is a flowchart of a capacitive touch sensing method according toan embodiment of the present invention.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

FIG. 1 is a schematic view illustrating a capacitive touch sensingcircuit according to an embodiment of the present invention. Thecapacitive touch sensing circuit 100 includes a switching capacitorintegrating circuit 110, a decoding circuit 120, a feedback circuit 130,and an encoding circuit 140. The switching capacitor integrating circuit110 is coupled to one terminal of a to-be-tested capacitive touch unitTUNT. The other terminal of the to-be-tested capacitive touch unit TUNTreceives a signal VIN. When a touch detecting action is performed on theto-be-tested capacitive touch unit TUNT, the signal VIN may be a clocksignal, and the to-be-tested capacitive touch unit TUNT may generate aninput signal IN and provide the input signal IN to the switchingcapacitor integrating circuit 110. The switching capacitor integratingcircuit 110 integrates the input signal IN received by the switchingcapacitor integrating circuit 110, so as to generate an output signalOUT.

In the present embodiment, the capacitance of the to-be-testedcapacitive touch unit TUNT may be changed according to whether theto-be-tested capacitive touch unit TUNT is touched or not, and the inputsignal IN may also be changed in response to variations in thecapacitance of the to-be-tested capacitive touch unit TUNT. Since theswitching capacitor integrating circuit 110 integrates the input signalIN, the integrated result can effectively reflect the changes to theinput signal IN, and whether the to-be-tested capacitive touch unit TUNTis touched or not can be determined according to the integrated result.On the other hand, the switching capacitor integrating circuit 110 maydetermine a reference voltage and compare the integrated result with thereference voltage, so as to generate the output signal OUT. In anembodiment of the present invention, the output signal OUT may be adigital signal, and a voltage level of the output signal OUT may stayunchanged or may be different in a plurality of continuous time cycles.

The encoding circuit 140 is coupled to the switching capacitorintegrating circuit 110 and receives the output signal OUT. The encodingcircuit 140 encodes the output signal OUT to generate an encoded resultER. The encoding circuit 140 may sequentially generate the encodedresult ER in a plurality of time cycles according to variations in avoltage of the output signal OUT in two successive time cycles.Particularly, the encoding circuit 140 may determine whether a logiclevel of the voltage of the output signal OUT remains constant (i.e.,logic high or logic low in both time cycles); if yes, the encodingcircuit 140 gradually increases the encoded result ER by 1. By contrast,if the logic level of the voltage of the output signal OUT is switchedfrom high to low or from low to high in the two successive time cycles,the encoding circuit 140 gradually decreases the encoded result ER by 1.For instance, if the high logic levels of the output signal OUT inplural successive time cycles are sequentially 1, 1, 1, 1, 0, 1, and 0,the encoded results ER generated by the encoding circuit 140 aresequentially 0, 1, 2, 3, 2, 1, and 0 (the default value is 0). Here, theminimum encoded result ER is 0.

The feedback circuit 130 is coupled to the switching capacitorintegrating circuit 110 and the encoding circuit 140. The feedbackcircuit 130 provides the switching capacitor integrating circuit 110with a charge dissipation path for discharging charges from theswitching capacitor integrating circuit 110. Here, the feedback circuit130 receives the encoded result ER and adjusts a charge dissipationability provided by the charge dissipation path according to the encodedresult ER. The feedback circuit 130 also receives the output signal OUTand determines to perform the charging action or the discharging actionaccording to the output signal OUT.

In the present embodiment, the feedback circuit 130 can adjust thecharge dissipation ability of the charge dissipation path provided tothe switching capacitor integrating circuit 110 according to the encodedresult ER. If the encoded result ER is a 3-bit numeral value, thefeedback circuit 130 is able to offer eight (2 ³) different chargedissipation abilities. If the charge dissipation ability provided by thefeedback circuit 130 is rather small, the sensing resolution of thecapacitive touch sensing circuit 100 can be enhanced; if the chargedissipation ability provided by the feedback circuit 130 is ratherlarge, the capacitive touch sensing circuit 100 can expand itsdetectable range of variations in the capacitance.

The decoding circuit 120 is coupled to the switching capacitorintegrating circuit 110. The decoding circuit 120 receives the outputsignal OUT and decodes the output signal OUT to generate a touchdetecting result DR. In detail, the decoding circuit 120 sequentiallygenerates a plurality of numeral values in a plurality of time cyclesaccording to variations in a voltage of the output signal OUT in twosuccessive time cycles and obtains the touch detecting result DR throughadding up the numeral values.

In light of the foregoing, the feedback circuit 130 of the capacitivetouch sensing circuit 100 can adjust the charge dissipation ability ofthe provided charge dissipation path according to the output signal OUTgenerated by the switching capacitor integrating circuit 110. Thecapacitive touch sensing circuit 100 can, according to its operatingconditions, make necessary modifications to satisfy the requirements forhigh resolution and the large detectable range, respectively, so as tooptimize the performance of the capacitive touch sensing circuit 100.

FIG. 2 is a schematic view illustrating a capacitive touch sensingcircuit according to another embodiment of the present invention. Thecapacitive touch sensing circuit 200 includes a switching capacitorintegrating circuit 210, a decoding circuit 220, a feedback circuit 230,and an encoding circuit 240. The switching capacitor integrating circuit210 is coupled to a capacitive touch unit TUNT. In the presentembodiment, the capacitive touch unit TUNT receives a signal VINgenerated by alternately switching on or off switches S1 and S2, and aninput signal IN is correspondingly generated. The signal VIN may be aperiodic signal transiting between a voltage of a reference groundterminal GND and a reference voltage Vref.

The switching capacitor integrating circuit 210 includes an operationalamplifier OP1, a capacitor Cop, a switch Sop, a comparator CMP1, and alatch LA1. The operational amplifier OP1 receives the input signal INand integrates the input signal IN through the switch Sop and thecapacitor Cop. An integrated result is generated by an output terminalof the operational amplifier OP1 and transmitted to the comparator CMP1.The comparator CMP1 compares the integrated result with a referencesignal VR to generate a comparison result, and the latch LA latches thecomparison result generated by the comparator CMP1, so as to generate anoutput signal OUT. The latch LA performs the data latching actionaccording to a clock signal CK.

The output signal OUT is transmitted to the decoding circuit 220, theencoding circuit 240, and the feedback circuit 230. The decoding circuit220 receives the output signal OUT and accordingly generates a detectingresult DR. The encoding circuit 240 receives the output signal OUT andencodes the output signal OUT to generate an encoded result ER.

The feedback circuit 230 includes a switching capacitive circuit 231.The switching capacitive circuit 231 receives the output signal OUT, anda first terminal of the switching capacitive circuit 231 is coupled toan end point of the switching capacitor integrating circuit 210receiving the input signal IN. The switching capacitive circuit 230includes a weighted capacitance adjuster 232. The weighted capacitanceadjuster 232 provides a capacitance Cfbv that can be adjusted accordingto the encoded result ER.

Based on the capacitance Cfbv provided by the weighted capacitanceadjuster 232, the charge dissipation ability of the charge dissipationpath provided by the feedback circuit 230 can be adjusted, and thecapacitive touch sensing circuit 200 can satisfy the requirements forboth the highly sensing resolution and the large detectable range ofvariations of the capacitance.

As to other details of the switching capacitive circuit 231, theswitching capacitive circuit 231 further includes switches S3, S4, S5,and S6. A first terminal of the switch S3 receives the input signal IN,and a second terminal of the switch S3 is coupled to a first terminal ofthe switch S4. A second terminal of the switch S4 is coupled to a firstterminal of the switch S5 and a first terminal of the switch S6, and asecond terminal of the switch S5 and a second terminal of the switch S6are respectively coupled to the reference ground terminal GND and thereference voltage Vref. The weighted capacitance adjuster 312 isserially coupled between the second terminal of the switch S4 and thereference ground terminal GND. The switches S5 and S6 may be switched onor off according to the same control signal, and the switches S3 and S4are switched on or off according to the output signal OUT. While theswitch S3 is switched on, the switch S4 is switched off, and vice versa.

In the present embodiment, the switches S5 and S6 may controlled by thecontrol signal CTR and may thus be switched on or off, and the switchesS3 and S4 are switched on or off according to the output signal OUT.While the switch S3 is switched on, the switch S4 is switched off, andvice versa. If the switch S4 is controlled by the output signal OUT andis switched on, the feedback circuit 230 provides the switchingcapacitor integrating circuit 210 with a charge dissipation path fordischarging charges from the switching capacitor integrating circuit210.

In detail, the decoding circuit 220 sequentially generates a pluralityof numeral values in a plurality of time cycles according to variationsin a voltage of the output signal OUT in two successive time cycles andobtains the touch detecting result DR through adding up the numeralvalues.

The encoding circuit 240 sequentially generates the encoded result ER ina plurality of time cycles according to variations in a voltage of theoutput signal OUT in two successive time cycles. Particularly, theencoding circuit 240 may determine whether a logic level of the voltageof the output signal OUT remains constant; if yes, the encoding circuit240 gradually increases the encoded result ER by 1. By contrast, if thelogic level of the voltage of the output signal OUT is switched fromhigh to low or from low to high in the two successive time cycles, theencoding circuit 240 gradually decreases the encoded result ER by 1.

Note that the decoding circuit 220 and the encoding circuit 240 can bothbe implemented in form of a digital circuit. That is, according to theaforesaid principles of circuit operations, the decoding circuit 220 andthe encoding circuit 240 can be implemented in form of any digitaldesign commonly known to people having ordinary skill in the pertinentart, such as a hardware description language (HDL), a conventional truthtable, a Karnaugh map, a Mealy finite state machine or a Moore finitestate machine, and so on. Hence, the decoding circuit 220 and theencoding circuit 240 do not have any fixed configuration. If thedecoding circuit 220 and the encoding circuit 240 are implemented inform of HDL, the database of the circuit synthesizer software and thebasic logic gate of the circuit employed by the designer determine thetype and the number of logic gates in the circuit, and the type and thenumber of logic gates may not remain constant.

FIG. 3 is a schematic view illustrating a capacitive touch sensingcircuit according to still another embodiment of the present invention.The capacitive touch sensing circuit 300 includes a switching capacitorintegrating circuit 310, a decoding circuit 320, a feedback circuit 330,and an encoding circuit 340. The feedback circuit 330 provided hereinnot only receives the output signal OUT but also receives the encodedresult ER. Different from the feedback circuit 230 provided in theaforementioned embodiment, the feedback circuit 330 provided hereinincludes the switching capacitive circuit 331 and a weighted voltageadjuster 332. The switching capacitive circuit 331 includes switchesS3-S6 and a capacitor Cfb. One terminal of the switch S3 receives theinput signal IN, and the other terminal of the switch S3 is coupled toone terminal of the switch S4. The other terminal of the switch S4 iscoupled to a first terminal of the switch S5 and a first terminal of theswitch S6, and a second terminal of the switch S5 and a second terminalof the switch S6 are respectively coupled to the reference groundterminal GND and the weighted voltage adjuster 332. The capacitor Cfb isserially connected between the reference ground terminal GND and theterminal where the switches S3 and S4 are coupled to each other.

The weighted voltage adjuster 332 provides a weighted voltage WV to thesecond terminal of the switch S6 and is able to adjust the weightedvoltage WV according to the encoded result ER. Through adjusting theweighted voltage WV, the feedback circuit 330 is able to effectivelyadjust the charge dissipation ability of the charge dissipation pathprovided by the feedback circuit 330.

For instance, if 8 different 3-bit hexadecimal encoded results ER (0-7)are provided, the weighted voltage WV can be adjusted within the range⅛*Vref− 8/8*Vref. That is, the feedback circuit 330 is able to make8-phase modifications to the charge dissipation ability of the chargedissipation path.

Certainly, the bit number of the encoded result ER is not limitedherein; if it is intended to increase the sensing resolution ofvariations in the capacitance, the bit number of the encoded result mayalso be increased. The feedback circuits can also make modifications tothe charge dissipation ability of the charge dissipation path in morephases.

FIG. 4 is a schematic view illustrating a capacitive touch sensingcircuit according to another embodiment of the invention. The capacitivetouch sensing circuit 400 includes a switching capacitor integratingcircuit 410, a decoding circuit 420, a feedback circuit 430, and anencoding circuit 440. Different from the feedback circuits provided inthe aforementioned embodiments, the feedback circuit 430 provided hereinincludes current sources I1 and I2 and switches S3 and S4. A firstterminal of the switch S3 and a first terminal of the switch S4 arecommonly coupled to an input end point of the switching capacitorintegrating circuit 410, and a second terminal of the switch S3 and asecond terminal of the switch S4 are respectively coupled to the currentsources I1 and I2. Note that the current source I2 drains the currentfrom the switch S4 and transmits the drained current to the referenceground terminal GND.

Note that the switches S3 and S4 are controlled by the output signalOUT, and the current sources I1 and I2 are controlled by the encodedresult ER. When the switch S3 is switched on, the switch S4 is switchedoff, and vice versa. Here, the amount of the current drained from thecurrent sources I1 and I2 or the time frame during which the charges aredischarged can be adjusted according to the encoded result ER and theoutput signal OUT. Thereby, the charge dissipation path provided by thefeedback circuit 410 is dynamically adjusted, e.g., thecharging/discharging ability of the charging/discharging path may beadjusted.

FIG. 5 illustrates waveforms of encoding actions of an encoding circuitaccording to an embodiment of the invention. The voltage level of theoutput signal OUT is periodically detected; at the time point T1 and thetime point T2, the output signal OUT has the same logic high level, andthe encoding circuit can gradually increase the encoded result ER from 0to 1 at the time point T2. At the time point T3, the encoding circuitdetects that the voltage level of the output signal OUT remains logichigh, and thus the encoding circuit gradually increases the encodedresult ER from 1 to 2 at the time point T3. At the time point T4, theencoding circuit continues to detect the voltage level of the outputsignal OUT and finds out that the voltage level of the output signal OUTremains logic high, and thus the encoding circuit gradually increasesthe encoded result ER from 2 to 3 at the time point T4.

At the time point T5, the encoding circuit detects that the voltagelevel of the output signal OUT is changed to logic low, and thus theencoding circuit gradually decreases the encoded result ER from 3 to 2at the time point T4. Similarly, at the time point T6, the encodingcircuit detects that the voltage level of the output signal OUT ischanged to logic high from logic low; at the time point T7, the encodingcircuit detects that the voltage level of the output signal OUT ischanged to logic low from logic high. Hence, the encoding circuitgradually decreases the encoded result ER from 2 to 1 at the time pointT6 and gradually decreases the encoded result ER from 1 to 0 at the timepoint T7.

FIG. 6 is a schematic view illustrating a touch apparatus according toan embodiment of the present invention. The touch apparatus 600 includesa touch panel 610 and at least one capacitive touch sensing circuit 620,and the touch panel 610 may be a self-capacitive touch panel or amutual-capacitive touch panel. The touch panel 610 includes a pluralityof capacitive touch units, and the to-be-tested capacitive touch unitTUNT of the capacitive touch units is coupled to the capacitive touchsensing circuit 620 to detect variations in the capacitance of theto-be-tested capacitive touch unit TUNT and thereby obtain the touchedcondition of the to-be-tested capacitive touch unit TLTNT. In thepresent embodiment, the touch panel 610 may be an in-cell touch displaypanel. However, in other embodiments, the touch panel 610 may be anout-cell touch panel or any other touch panel capable of performing thetouch function.

The capacitive touch sensing circuit 620 may be implemented by any ofthe capacitive touch sensing circuits 200, 300, and 400 depicted in FIG.2, FIG. 3, and FIG. 4, and the implementation details of the capacitivetouch sensing circuits 200, 300, and 400 are already elaborated in theaforementioned embodiments and therefore will not be provided herein.

FIG. 7 is a flowchart of a capacitive touch sensing method according toan embodiment of the present invention. In step S710, a to-be-testedcapacitive touch unit receives an input signal and provides a switchingcapacitor integrating circuit to integrate the input signal, so as togenerate an output signal; in step S720, the output signal is encoded togenerate an encoded result; in step S730, a charge dissipation path isprovided to the switching capacitor integrating circuit for dischargingcharges from the switching capacitor integrating circuit and adjusting acharge dissipation ability provided by the charge dissipation pathaccording to the encoded result; in step S740, the output signal isdecoded to generate a touch detecting result.

The implementation details of each step are already elaborated above andthus will not be repeated.

To sum up, the encoding circuit provided herein encodes the outputsignal, and the encoded result is provided to the feedback circuit. Thefeedback circuit dynamically adjusts the charge dissipation ability ofthe charge dissipation path provided by the feedback circuit accordingto the encoded result; thereby, the capacitive touch sensing circuitneed not sacrifice the detectable range of variations in the capacitancefor the highly sensing resolution nor sacrifice the resolution for thelarge detectable range of variations in the capacitance. That is, thecapacitive touch sensing circuit provided herein can function whiletaking the requirements for both the resolution and the detectable rangeinto consideration, and the performance can therefore be enhanced. Itwill increase the sensitivity of touch apparatus using the capacitivesensing circuit according to the embodiments of the present invention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of thedisclosed embodiments without departing from the scope or spirit of thedisclosure. In view of the foregoing, it is intended that the disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. A capacitive touch sensing circuit comprising: aswitching capacitor integrating circuit coupled to a to-be-testedcapacitive touch unit receiving an input signal, the switching capacitorintegrating circuit integrating the input signal to generate an outputsignal. an encoding circuit coupled to the switching capacitorintegrating circuit to receive the output signal and encode the outputsignal to generate an encoded result; a feedback circuit coupled to theswitching capacitor integrating circuit and the encoding circuit, thefeedback circuit providing the switching capacitor integrating circuitwith a charge dissipation path for discharging charges from theswitching capacitor integrating circuit, the feedback circuit receivingthe encoded result and adjusting a charge dissipation ability providedby the charge dissipation path according to the encoded result; and anencoding circuit coupled to the switching capacitor integrating circuitto receive the output signal and decode the output signal to generate atouch detecting result.
 2. The capacitive touch sensing circuit asrecited in claim 1, wherein the feedback circuit comprises: a switchingcapacitive circuit receiving the output signal, a first terminal of theswitching capacitive circuit being coupled to an end point of theswitching capacitor integrating circuit receiving the input signal; anda weighted voltage adjuster coupled to the encoded circuit and a secondterminal of the switching capacitive circuit, the weighted voltageadjuster providing a weighted voltage to the second terminal of theswitching capacitive circuit and adjusting the weighted voltageaccording to the encoded result, wherein the charge dissipation path isgenerated between the first terminal and the second terminal of theswitching capacitive circuit.
 3. The capacitive touch sensing circuit asrecited in claim 2, wherein the switching capacitive circuit comprises:a first switch, a first terminal of the first switch being coupled tothe end point of the switching capacitor integrating circuit receivingthe input signal, the first switch being controlled by the output signalto be switched on or off; a capacitor serially connected between asecond terminal of the first switch and a reference ground terminal; asecond switch, a first terminal of the second switch being coupled tothe second terminal of the first switch, the second switching beingcontrolled by the output signal to be switched on or off; a third switchserially connected between a second terminal of the second switch andthe reference ground terminal and controlled by a control signal to beswitched on or off; and a fourth switch, a first terminal of the fourthswitch being coupled to the second terminal of the second switch, asecond terminal of the fourth switch receiving the weighted voltage, thefourth switch being controlled by the control signal to be switched onor off.
 4. The capacitive touch sensing circuit as recited in claim 1,wherein the feedback circuit comprises: a switching capacitive circuitreceiving the output signal, a first terminal of the switchingcapacitive circuit being coupled to an end point of the switchingcapacitor integrating circuit receiving the input signal, the switchingcapacitive circuit comprising a weighted capacitance adjuster providinga capacitance, the capacitance being adjusted according to the encodedresult, wherein a second terminal of the switching capacitive circuitreceives a reference voltage, and the charge dissipation path isgenerated between the first terminal and the second terminal of theswitching capacitive circuit
 5. The capacitive touch sensing circuit asrecited in claim 4, wherein the feedback circuit further comprises: afirst switch, a first terminal of the first switch being coupled to theend point of the switching capacitor integrating circuit receiving theinput signal, the first switch being controlled by the output signal tobe switched on or off; a second switch, a first terminal of the secondswitch being coupled to a second terminal of the first switch, thesecond switch being controlled by the output signal to be switched on oroff; a third switch serially connected between a second terminal of thesecond switch and a reference ground terminal and controlled by acontrol signal to be switched on or off; and a fourth switch, a firstterminal of the fourth switch being coupled to the second terminal ofthe second switch, a second terminal of the fourth switch receiving thereference voltage, the fourth switch being controlled by the controlsignal to be switched on or off
 6. The capacitive touch sensing circuitas recited in claim 1, wherein the feedback circuit comprises: a switch,a first terminal of the switch being coupled to an end point of theswitching capacitor integrating circuit receiving the input signal; anda current source coupled to a second terminal of the switch, the currentsource draining a current from the second terminal of the switch andtransmitting the current to a reference ground terminal, wherein anamount of the current or a time frame during which the switch isswitched on is adjusted according to the encoded result.
 7. Thecapacitive touch sensing circuit as recited in claim 1, wherein theencoding circuit sequentially generates the encoded result in aplurality of time cycles according to variations in a voltage of theoutput signal in two successive time cycles of the time cycles.
 8. Thecapacitive touch sensing circuit as recited in claim 7, wherein theencoding circuit gradually increases the encoded result when a logiclevel of the voltage of the output signal in two successive time cyclesof the time cycles remains constant, and the encoding circuit graduallydecreases the encoded result when the logic level of the voltage of theoutput signal in one of the two successive time cycles is different fromthe logic level of the voltage of the output signal in the other of thetwo successive time cycles.
 9. The capacitive touch sensing circuit asrecited in claim 1, wherein the decoding circuit sequentially generatesa plurality of numeral values in a plurality of time cycles according tovariations in a voltage of the output signal in two successive timecycles of the time cycles and obtains the touch detecting result throughadding up the numeral values.
 10. A touch apparatus comprising: a touchpanel comprising a plurality of capacitive touch units; and at least onecapacitive touch sensing circuit as recited in claim 1, the at least onecapacitive touch sensing circuit being coupled to the to-be-testedcapacitive touch unit of one of the capacitive touch units.
 11. Acapacitive touch sensing method comprising: receiving an input signal,providing a switching capacitor integrating circuit, and integrating theinput signal by a switching capacitor integrating circuit, so as togenerate an output signal; encoding the output signal to generate anencoded result; providing the switching capacitor integrating circuitwith a charge dissipation path for discharging charges from theswitching capacitor integrating circuit and adjusting a chargedissipation ability provided by the charge dissipation path according tothe encoded result; and decoding the output signal to generate a touchdetecting result.
 12. The capacitive touch sensing method as recited inclaim 11, wherein the step of providing the switching capacitorintegrating circuit with the charge dissipation path for discharging thecharges from the switching capacitor integrating circuit and adjustingthe charge dissipation ability provided by the charge dissipation pathaccording to the encoded result comprises: providing a switchingcapacitive circuit, a first terminal of the switching capacitive circuitbeing coupled to the switching capacitor integrating circuit; andproviding a weighted voltage to a second terminal of the switchingcapacitive circuit and adjusting the weighted voltage according to theencoded result, wherein the charge dissipation path is formed betweenthe first terminal and the second terminal of the switching capacitivecircuit.
 13. The capacitive touch sensing method as recited in claim 11,wherein the step of providing the switching capacitor integratingcircuit with the charge dissipation path for discharging the chargesfrom the switching capacitor integrating circuit and adjusting thecharge dissipation ability provided by the charge dissipation pathaccording to the encoded result comprises: providing a switchingcapacitive circuit, a first terminal of the switching capacitive circuitbeing coupled to the switching capacitor integrating circuit; andadjusting a capacitance of a variable capacitor in the switchingcapacitive circuit according to the encoded result, wherein a secondterminal of the switching capacitive circuit receives a referencevoltage, and the charge dissipation path is formed between the firstterminal and the second terminal of the switching capacitive circuit.14. The capacitive touch sensing method as recited in claim 11, whereinthe step of providing the switching capacitor integrating circuit withthe charge dissipation path for discharging the charges from theswitching capacitor integrating circuit and adjusting the chargedissipation ability provided by the charge dissipation path according tothe encoded result comprises: providing a switch, the switch beingcoupled between an end point of the switching capacitor integratingcircuit receiving the input signal and a current source; enabling thecurrent source to drain a current from a second terminal of the switchand transmit the current to a reference ground terminal; and adjustingat least one of an amount of the current and a time frame during whichthe switch is switched on according to the encoded result.
 15. Thecapacitive touch sensing method as recited in claim 11, wherein the stepof encoding the output signal to generate the encoded result comprises:sequentially generating the encoded result in a plurality of time cyclesaccording to variations in a voltage of the output signal in twosuccessive time cycles of the time cycles.
 16. The capacitive touchsensing method as recited in claim 15, wherein the step of sequentiallygenerating the encoded result in the time cycles according to thevariations in the voltage of the output signal in the two successivetime cycles comprises: gradually increasing the encoded result when alogic level of the voltage of the output signal in the two successivetime cycles remains constant; and gradually decreasing the encodedresult when the logic level of the voltage of the output signal in oneof the two successive time cycles is different from the logic level ofthe voltage of the output signal in the other of the two successive timecycles.
 17. The capacitive touch sensing method as recited in claim 11,wherein the step of decoding the output signal to generate the touchdetecting result comprises: sequentially generating a plurality ofnumeral values in a plurality of time cycles according to variations ina voltage of the output signal in two successive time cycles of the timecycles; and adding up the numeral values to obtain the touch detectingresult.